There's no shortage of theories for stopping the Asian carp's move toward the Great Lakes. Big gates, underwater electric barriers, annoying sound -- all have been used or talked about as solutions.

Now, add bubbles. That was the winning idea from "Carp Tank," a $500,000 competition that wrapped up in Michigan this week.

Edem Tsikata, a software consultant in Massachusetts, took first prize with a plan to use a row of specially designed propellers to generate a wall of bubbles that implode and emit high-speed jets of water. The painful sensation of the bubbles -- and the noisy propellers -- aim to repel the fish.

Tsikata, who won $200,000, works for Ab Initio Software in Lexington. In a statement announcing the winners, he said, "It's gratifying to be able to contribute ideas that benefit the economy and ecology of [the Great Lakes] region even though I live in Boston."

Other ideas from contest finalists would target the fish with chlorine, strong currents and recognition software.

Michigan Gov. Rick Snyder announced the Great Lakes Invasive Carp Challenge last year. He and other judges assessed entries on their feasibility, environmental impact and other factors.

Millions of dollars have been spent already to keep the invasive species out of the Great Lakes, and defenses are concentrated near the southern tip of Lake Michigan.

Two varieties of Asian Carp -- the Silver and Bighead -- pose the biggest threat because of their voracious feeding habits. They consume lots of zooplankton, the microscopic animals that other fish feed on.

The issue got new attention in June, when a live Asian carp was discovered beyond an electric barrier, just nine miles from Lake Michigan.

The report says the underwater electric barrier at the Brandon Road lock in Illinois should be beefed up. The recommended $275 million plan would add water jets and complex noises – like the underwater recordings of a boat motor.

The report says the current defense at the Brandon Road lock in Illinois – an underwater electric barrier – should be beefed up. The Army Corps' recommended plan would add water jets and complex noises – like the underwater recordings of a boat motor.